1. Field of Invention
The present invention relates to a projector including an electro-optical device for forming optical images according to image information.
2. Description of Related Art
There are conventionally-known projectors including a light source, a electro-optical device for forming optical images of light flux emitted from the light source according to image information, a projecting lens for performing enlarged projection of the image formed with this electro-optical device, and an external case for storing these components.
Such projectors are widely used for multimedia presentations at conferences, academic meetings, exhibitions, etc., and reduction in size is being promoted since the projectors may be brought in a necessary or moved to another location for storage after usage.
Also, high luminance of light source lamps serving as the light source is being promoted, in order to make the projected images from the projector clear.
With such projectors having high luminance and reduced size, the temperature within the device tends to rise, so there is the need to efficiently cool the electro-optical device which is weak to heat.
Accordingly, an air intake is formed at the lower plane of the exterior case, and a cooling fan for introducing external air as cooling air from the air intake is provided below the electro-optical device, thereby cooling the electro-optical device.
However, with the above conventional projector, there is the need to have the center of gravity at a low position in order to secure stability at the time of being set up, so the height-wise dimensions from the desktop, or the like, on which the projector is set to the lower plane of the exterior case is made to be small. Accordingly, even in the event that introduction of great amounts of cooling air from the lower plane of the projector using the cooling fan is attempted, there is a limit to the amount of air which can be introduced through the gap portion, and particularly, with projectors having high luminance and reduced size, there is the problem that cooling of the electro-optical device cannot be performed sufficiently.
The present invention provides a projector that includes a cooling structure which effectively cools the electro-optical device and which can deal with high luminance of light source lamps and reduction in size of the apparatuses. The projector may include an electro-optical device for forming optical images according to image information and an exterior case for covering a main unit containing the electro-optical device, wherein an air intake opening for intake of external air as cooling air is formed at the upper plane of the exterior case, and a cooling fan for introducing the cooling air from the air intake opening and cooling the electro-optical device is provided above the electro-optical device.
According to the present invention, the upper plane of the exterior case is usually opened upwards, so an air intake is provided on this upper plane, and a cooling fan for introducing cooling air from this air intake to the inside of the apparatus is provided above the electro-optical device, whereby cooling air sufficient for cooling the electro-optical device can be easily blown onto the electro-optical device. Thus, the electro-optical device can be cooled efficiently, and a cooling structure capable of dealing with high luminance of light source lamps and reduction in size of the apparatuses can be obtained.
In the above, it is preferable for the projector to have a projecting lens for enlarged projection of images formed by the electro-optical device, and the projecting lens to have a plurality of lenses positioned following a predetermined axis, with the lens of the plurality of lenses positioned at the base edge closest to the projecting direction at least notched at the upper edge side thereof.
The electro-optical device may be provided near the base edge of the projection lens, so arranging for the center of the image forming area of the electro-optical device to be positioned lower than the intersection of an extended line from the axis of the projection lens and the electro-optical device causes the optical image from the electro-optical device to be cast in from the lower side of the axis, and to be projected by passing through the projecting lens and expanding above the axis. Accordingly, even in the event that the upper edge side of the lens positioned at the side closest to the base edge is notched, there is no problem, and an optical image is enlarged and projected into a projecting plane.
Accordingly, with the upper edge of the lens in a notched form, the cooling fan provided above the electro-optical device can be positioned closer to the electro-optical device by an degree equivalent to the degree of the notching of the upper edge. Thus, cooling air with great force can be introduced to the electro-optical device, so cooling of the electro-optical device can be performed even more efficiently. Also, positioning the cooling fan closer to the electro-optical device reduces the height-wise dimensions of the projector, so the projector can be made smaller and thinner.
Also, a light shielding structure for preventing light from leaking from the air intake opening is preferably provided above the cooling fan.
Thus, light can be prevented from leaking from the air intake, thus improving the visual recognition of the image by observers which generally observe the image from behind the apparatus.
Further, the light shielding structure is preferably formed in a louver-like configuration wherein a plurality of plate-shaped members positioned in a parallel manner across the air intake opening so as to assume a predetermined angle with the planes thereof as to the opening plane of the air intake opening. Specifically, inclining the plate-shaped members so as to descend toward the rear side of the apparatus or inclining so as to descend toward the front side of the apparatus changes the direction of the gaps between the plate-shaped members, so the direction of emission of leaking light can be restricted. Now, inclining the plate-shaped members so as to descend toward the rear side of the apparatus causes leaking light to be emitted forwards from the apparatus, so leaking light is not cast into the eyes of the observers, and the visual recognition of the image by observers observing the image from behind or beside the apparatus can be further improved. That is, with an arrangement wherein the multiple plate-shaped members assume a predetermined angle with the planes thereof as to the opening plane of the air intake opening, there is hardly any light leaking out. Moreover, cooling air can be introduced to the cooling fan from the gaps between the plate-shaped members. Accordingly, employing a louver-like configuration of plurality of plate-shaped members as the light shielding structure allows prevention of leaking light and introduction of cooling air to be performed with a single light-shielding structure, so there is no increase in the number of parts for the projector, and the projector can be reduced in size from this perspective, as well.
Also, an exhaust opening for exhausting air within the projector externally is preferably provided to the front plane of the exterior case.
Thus, the air taken inside the apparatus with the cooling fan can be exhausted forward from the apparatus, so the exhausted air does not blow on observers observing the image from behind or beside the apparatus, so the observers do not feel discomfort from this perspective as well.
Also, the exhaust is formed at the front plane of the exterior case, so light leaking from the exhaust is not recognized by observers observing the image from behind or beside the apparatus, so visual recognition of the image by the observers can be improved. Incidentally, providing the exhaust with a light-shielding structure for preventing leaking of light from the exhaust can prevent light from leaking from the exhaust.
Further, the aforementioned projector preferably includes a projecting lens for enlarged projection of the image formed with the electro-optical device, and an optical parts housing for storing optical parts, wherein the projecting lens and the optical parts housing are combined and positioned in a planar U-shape having a recession portion, the recession portion faces the front side of the exterior case, an electric power source unit for supplying electric power to driving circuit boards, and the like, for driving the electro-optical device is positioned at the recession portion, and a device fan for exhausting air which has been taken in with the cooling fan and has cooled the internal parts of the projector outside of the projector and a electric power source fan for independently exhausting air which has been heated by the electric power source unit are provided at the exhaust.
Now, the electric power source unit for providing electricity to the driving circuit board, and the like, heats up, but the surrounding area thereof is surrounded by the optical parts housing and the projecting lens, so there is nowhere for the heat to escape. Accordingly, providing an exhaust and an exhaust fan dedicated to the electric power source unit allows the air heated by the electric power source unit to be aggressively exhausted. Thus, the rise in temperature of the electric power source unit can be suppressed, and stabilizing of the electric power source unit can be easily realized.
Also, preferably, a temperature detecting device for detecting the temperature of the cooling air near the electric power source unit is provided near the electric power source unit, and the electric power source fan is independently controlled by the temperature detected by the temperature detecting device.
Now, the temperature detecting device is preferably configured so as to output detecting signals to the control board for controlling the electric power source fan. Configuring the temperature detecting device such allows control wherein, e.g., in the event that detecting is made that the temperature of the electric power source unit is high, the number of revolutions of the electric power source fan is increased so as to rapidly cool the electric power source unit, and conversely in the event that detecting is made that the temperature of the electric power source unit is low, the number of revolutions of the electric power source fan is lowered so as to gradually cool the electric power source unit.
Incidentally, the reference temperature serving as a reference for high and low for the detected temperature should be determined as appropriate based on results obtained by experimentation, and the like.
Thus, rapid rises in temperature due to providing electric power to the driving circuit board, and the like, can be prevented, and prevention of heating of the electric power source unit can be easily realized.
Also, a preferable arrangement has a lamp driving circuit board for driving the lamp at the side of the U-shaped main unit placed in a planar U-shaped form by combining the projecting lens and the optical parts housing, wherein the lamp driving circuit board has a cooling air intake channel for introducing cooling air taken in by the cooling fan and is covered by a protective cover member and formed between the projecting lens and the optical parts housing, wherein an exhaust channel for leading the cooling air which has been introduced from the cooling air intake channel and which has cooled the electro-optical device to the device fan is formed between the lower plane of the optical parts housing and the inner lower plane of the exterior case, and wherein an opening for introducing a part of the cooling air flowing through the exhaust channel is formed to the protective cover member.
Thus, the inside of the protective cover member can be cooled as well, so cooling within the projector can be performed even more efficiently.
Also, intake and exhaust channels are formed, so circulation of air is conducted in an efficient manner, and the cooling efficiency of the electro-optical device improves even further. Further, the cooling air intake channel and exhaust channel are thus formed, so the structure within the projector can be simplified, and causing the cooling air to flow at the bottom of the optical parts housing allows the optical parts positioned within the housing, such as the lenses, mirrors, etc., to also be easily cooled.
Also, the projector preferably is arranged such that the electro-optical device has a plurality of light modulation devices, a prism for synthesizing light modulated by the plurality of light modulation devices, and an optical parts housing which stores optical parts other than the projecting lenses, the light modulation devices, and the prism, and is formed so as to envelop the light incidence plane of the light modulating device, wherein a rectifying plate for introducing cooling air from the cooling fan to the light modulating devices is provided at the gap between the optical parts housing and the prism.
Thus, cooling air from the cooling fan can be guided to the light modulating devices with the rectifying plate, so circulation of the air flowing through the gap between the optical parts housing and the prism is conducted in an efficient manner, and the cooling efficiency of the light modulating devices improves even further.
Further, the rectifying plate is preferably attached to the optical parts housing.
Thus, simply attaching the optical parts housing to the exterior case is sufficient, and there is no need to provide in the apparatus a separate structure for supporting the rectifying plate, thus enabling simplifying of the structure. Accordingly, ease of the task of attaching the rectifying plate is facilitated, further facilitating ease of the task of assembling the projector.
Also, preferably, the optical parts housing has a fan attachment portion for fixing the cooling fan, and the rectifying plate is attached between the fan attachment portion and the cooling fan.
Thus, the rectifying plate is positioned directly below the cooling fan, so the cooled air introduced within the apparatus from the cooling fan can be guided and blown on the light modulating devices. Thus, the cooling efficiency of the light modulating device improves even further.
Further, the rectifying plate preferably has an attaching piece which is attached to the fan attachment portion, and an extending piece which extends from the edge portion of the attaching piece toward the light modulating devices, wherein the tip of the extending piece is positioned lower than the cooling fan side edge of the image forming area of the light modulating devices.
The image forming area relates to the area at the center of the modulating device used for forming images. Light is concentrated at this area, and particularly easily overheats. Also, in the event that a material which easily changes modulation properties by heat, such as liquid crystal is used, temperature rising in the image forming area may cause deterioration in the image quality.
Accordingly, positioning the tip of the extending piece of the rectifying plate lower than the cooling fan side edge of the image forming area enables cooling air to be blown against the extended piece and thus, directly blown onto the image forming area, and consequently, such problems can be reduced.
Further, in the event of forming the electro-optical device from three light modulating devices which perform modulation of red, green, and blue light fluxes, blue light has greater energy than the other color lights, and the image forming area of the modulating device which performs modulation of this light easily overheats, so placing the rectifying plate near the light modulating device which performs modulation of the blue light flux enables rapid temperature rising of the light modulating device to be suppressed. Accordingly, the cooling efficiency of the electro-optical device can be improved even further.